Polarity Modulation in MoTe₂ Vertical Transistors via Contact Metallization Engineering

Vertical field-effect transistors (V-FETs) based on two-dimensional materials (2DMs) have emerged as promising candidates for beyond-silicon nanoelectronics, as their effective channel length is defined by the material thickness rather than lithographic resolution. However, achieving controllable polarity modulation in 2DM-based V-FETs using homogeneous semiconductor channels remains a significant challenge. Here, we investigate process-induced polarity modulation in MoTe₂based V-FETs through contact metallization engineering. We demonstrate that different metallization processes lead to distinct carrier polarities: devices with directly evaporated Au contacts exhibit n-type conduction, whereas devices incorporating van der Waals (vdW)-transferred Au electrodes show pronounced p-type behavior. This polarity transition is attributed to the suppression of metal-induced gap states at vdW interfaces, which effectively weakens Fermi-level pinning and restores the intrinsic band alignment of MoTe₂. These results establish a doping-free and metal-independent approach for achieving polarity-controllable complementary V-FETs based on homogeneous two-dimensional semiconductors, providing a viable pathway toward scalable vertical CMOS architectures.